1. Field of the Invention
The present invention relates to a monitoring device for overhead electric power transmission system or power distribution system and more particularly to a monitoring device for monitoring condition of the power transmission system or power distribution system such as an abnormal current flowing in overhead power transmission lines and/or an overhead ground wire when accident or lightning stroke occur, wire vibration or wire temperature and so on.
2. Background of the Invention
In a conventional monitoring device of the type mentioned above, a current detecting unit such as a current transformer is directly mounted to an overhead ground line which is suspended by means of anchor and clamp members coupled to arms of steel towers of an overhead power transmission system. In such case, the current transformer is mounted to the overhead ground wire by passing the overhead ground wire through the center hole of the current transformer, and the current transformer is fastened to the overhead ground wire only by the friction between the overhead ground wire and the current transformer.
In the conventional arrangement as mentioned above, the clamping force of the current transformer to the overhead ground wire is gradually weakened due to the vibration of the ground wire and the secular variation, whereby the current transformer may be moved along the ground wire, resulting in damage of the ground wire. Therefore, in the conventional arrangement, it is difficult to guarantee the ability of detection of the conventional monitoring device for a long time and reliability of the monitoring device is relatively low.